This invention relates generally to bag filling machines and more specifically to an improved structure and method for use with a bag filling machine which is designed to improve material flow in the filling machine while minimizing dust and particle distribution resulting from suspended turbulent air by generating the dust in an area where it may be more easily removed.
Prior art techniques of filling fine powdery materials into bags in a bag filling machine have consisted of filling the bags through a valve bag opening wherein the product is aerated and blown through a tube three to four inches in diameter. This method also results in a dispersal or dusting of the product but not to the same degree as would occur in the use of an open mouth bag. When utilizing such valve bag filling methods, disadvantages are obtained in that the number of bags that can be filled per minute is considerably reduced as a result of the small opening through which the product must flow and the ability of the air to escape from the container into which the product is forced. Higher line speeds have been obtained on valve packing equipment by utilizing multiple spout capabilities with varying degrees of success and with higher additional costs. A further disadvantage of the valve bag filling methods lies in the fact that in order to contain the product within the package, it is necessary to use what is known as a tuck-in sleeve in the valve in order to eliminate sifting of the product from the package after filling.
It has been felt by the applicant that open mouth multi-wall bags may be utilized to alleviate the problems inherent in valve bag filling and would also provide advantages over such filling techniques in that the filling charge may be placed more evenly in the container to be filled since access to the container or bag is through the fully opened mouth of the bag and not through a restricted tube. Further advantages are felt to exist when utilizing a pinch-style open mouth multi-wall bag since such bags are generally provided with sift-proof closures without the need of additional closing capabilities.
The filling of fine powdery materials into open mouth multi-wall bags has not been without problems which are generally related to excessive leakage and dispersion of the product from the filling system. In the prior art of filling open mouth bags, the falling material was allowed to impact at the bottom of the container being filled thereby generating dust in an area very difficult to evacuate. When filling materials such as manganese sulfate, several problems occur which must be solved in order that the manganese sulfate be accurately weighed and deposited in the bag that is being filled. The fine powdery materials such as manganese sulfate often flow like water in the transition chutes of standard bag filling machines and cause extreme dust problems and turbulence within the portions of the transition chute and the throat sections of the bag filling machine such that many other problems are encountered in removing the dust that must be met in order to obtain an acceptable filling machine from the customer's viewpoint. Since manganese sulfate does flow like water in the transition chute, its flow must be slowed down and accurately controlled while at the same time being allowed to pass through the transition chute fast enough to meet desired filling flow rates without causing excessive turbulence in the transition chute and generating dust in hard-to-remove areas.
It is known in prior art bag filling machines to provide automatic controls in the hopper to control the flow of material being fed into the bag or container. One such control device is shown in the U.S. Pat. No. 1,397,932, issued to J. B. Mockridge on Nov. 22, 1921, wherein a control device was developed for use with fertilizer and with industries developing more or less sticky materials in the plant. Such a control device, while satisfactory for fertilizer and other materials, would not necessarily be able to be adapted for fine powdery materials such as manganese sulfate or the like.
Other known prior art devices for controlling the flow of material in a transition chute for a filling device are taught in the U.S. Pat. No. 787,396, issued to P. Provost on Apr. 18, 1905, wherein there is taught a conical shaped regulator 14, shown in FIG. 1 of his drawing, with an angular obstruction 20 formed on the bottom of the cone for retarding the flow of grain for which the device was designed. Such conical shaped regulator, while satisfactory for grain would not necessarily be found desirable and satisfactory for use in bagging fine powdery materials such as manganese sulfate of the like. Other bag filling machines have been developed as typified by the U.S. Pat. No. 915,847, issued to P. A. Frye, on Mar. 23, 1909, which utilized conical shape shut-off valves 35, as shown in FIG. 1 of his patent, in combination with a revolving agitator 33 to control the flow of granular material such as flour or sugar. Such a machine as typified in this patent would probably be satisfactory for flour or sugar which would require the use of the revolving agitator but such combinations would not necessarily be required or even helpful in finer powdery substances such as manganese sulfate or the like.
More modern bag filling machines are typified in the U.S. Pat. No. 3,474,836, issued to P. Schwake, et al., on Oct. 28, 1969, wherein there is taught the use of at least two conical valves, shown by the numeral 3 and by the numeral 45 in FIG. 1 of the Schwake patent. The conical valve 45 has been designed to assure a disturbance-free flowing of the material out of the hopper and has been designed to distribute the material so that it emerges from the outlet free from eddie currents. How such distribution is obtained is not entirely explained, however, it is noted that the valve 45 in the patent is not movable in position during the filling operation with any given material which is diametrically opposite to the applicant's control device as will be more fully described hereinafter.
More recent use of conical valves in bag filling machines is also typified in the U.S. Pat. No. 3,578,041, issued to Katsuji Obara on May 11, 1971; and the U.S. Pat. No. 3,707,172, issued to the same inventor on Dec. 26, 1972. Such machines as typified by these two patents appear to utilize cone valves simply as flow control devices and not necessarily as utilized in the applicant's new and novel structure as will be more fully detailed hereinafter.